Reports have been made on obtainment of the antitumor substances from various kinds of Basidiomycetes in recent years. These substances have a polysaccharide structure and show a significant antitumor or anti-cancer effect in intraperitoneal administrations, but they prove to be extremely low in antitumor activities when administered orally. Therefore, although these substances could be of much interest for scientific studies, their practical utility is scarce.
It is also known that the extracts obtained by extracting fungi belonging to the Coriolus with an aqueous solvent are predominantly composed of protein-bound polysaccharides. However, as these extracts are obtained from native Basidiomycetes and contain complicated compounds composed of various kinds of protein-bound polysaccharides, no definite elucidation has yet been made on the characters of the active antitumor ingredients of these extracts.